Intramedullary fixation devices

ABSTRACT

An intramedullary fixation device used in bone fixation and stabilization on a patient includes a longitudinally extending rigid body, a distal head disposed at a distal end of the body and sized for insertion into an intramedullary canal of a phalanx of the patient, the distal head having a central core portion and a plurality of extending distal wings radially projecting from the central core portion. A proximal head at a proximal end of the body is sized for insertion into an intramedullary canal of a phalanx of the patient. It has a central core portion and a plurality of proximal wings extending radially outwardly from the central core portion.

BACKGROUND

This Application is a Continuation application of U.S. National Stageapplication Ser. No. 14/776,066 filed on Sep. 14, 2015, which is anational stage filing of International Application No. PCT/US2014/024485filed on Mar. 12, 2014, published as WO2014/165123 A1 on Oct. 9, 2014,which claims priority benefit of U.S. Provisional Application No.61/780,360 filed on Mar. 13, 2013. These applications, along with U.S.application Ser. No. 14/206,171 filed on Mar. 12, 2014, are incorporatedherein by reference in their entireties.

Hammertoe deformities occur when the metatarsophalangeal joint betweenphalanges in a toe are cocked upward and the proximal interphalangealjoint bends downward. This deformity can become quite painful and canlimit the ability of a person with hammertoe to walk and perform otherdaily activities. Hammertoe may be caused by any number of factors,including heredity, the long-term use of poorly fitting shoes, having along second toe, hallux valgus pressing against the second toe,connective tissue disorders and trauma.

While some minor cases may be treated with non-surgical remedies,surgeries are often necessary to provide real correction and painrelief. Some surgical methods include stabilizing the toes using asmooth K-wire placed in an antegrade manner through the middle anddistal phalanges while joint extension and distraction are maintained.The K-wire may then be placed in retrograde fashion into the proximalphalanx while joint extension and distraction are maintained. Fixationlasts for 4-6 weeks after surgery. During that time, the pins are cappedso that the sharp ends do not catch on objects, such as bed sheets. Evenwith this form of fixation, non-unions, K-wire migration, and loss offixation can be quite common. Further, the external K-wires may lead topin tract infections or movement of bone along the smooth wire,including rotation of the distal aspect of the toe. These types ofchallenges make alternative fixation methods desirable.

The system and methods disclosed herein overcome one or more of thedeficiencies of the prior art.

SUMMARY

In one exemplary aspect, the present disclosure is directed to anintramedullary fixation device used in bone fixation and stabilizationon a patient. The device includes a longitudinally extending rigid bodyand a distal head disposed at a distal end of the body. The distal headis sized for insertion into an intramedullary canal of a phalanx of thepatient. The distal head has a central core portion and a plurality ofextending distal wings radially projecting from the central coreportion. A proximal head at a proximal end of the body is sized forinsertion into an intramedullary canal of a phalanx of the patient. Ithas a central core portion and a plurality of proximal wings extendingradially outwardly from the central core portion.

In an exemplary aspect, the present disclosure is directed to anintramedullary fixation device used in bone fixation and stabilization.The device includes an arrowhead-shaped distal head comprising a distalend having a distal tip, with the distal head having first, second,third, and fourth outwardly facing side surfaces forming a pyramidalshape. The first and third side surfaces may be opposed from each otherand form a first angle, and the second and fourth side surfaces may beopposed from each other and form a second angle. The second angle isdifferent than the first angle. Each of the first and third sidesurfaces have a proximally projecting edge forming a tip of a barb,where the barbs are configured to engage tissue and inhibit rotationalmovement and inhibit axial movement of the distal head in a proximaldirection. The distal head has a first dimensional width measuredbetween proximally projecting edges of the first and third sidesurfaces. The device also includes an arrowhead-shaped proximal headcomprising a proximal end having a proximal tip. The proximal head hasfifth, sixth, seventh, and eighth outwardly facing side surfaces. Thefifth and seventh side surfaces may be opposed from each other and forma third angle, and the sixth and eighth side surfaces may be opposedfrom each other and form a fourth angle. The third angle is differentthan the fourth angle. Each of the fifth and seventh side surfaces has adistally projecting edge. The proximal head includes a trailing edgesurface intersecting the distally projecting edge of the fifth andseventh side surfaces, with the trailing edge surface extending in adirection substantially perpendicular to a longitudinal direction of theproximal head and intersecting with a neck region. The proximal head hasa second dimensional width measured between distally projecting edges ofthe fifth and seventh side surfaces, with the second dimensional widthbeing within the range of about 1.3-1.5 times the first dimensionalwidth. A rigid body extends between and connects the distal head and theproximal head. The rigid body has a neck region joined to the trailingedge surface of the proximal head in a manner that the trailing edgesurface is perpendicular to a longitudinal axis of the body. The bodyhas a rigidity sufficient to withstand bending loading applied by thephalanges.

In an aspect, the first angle is smaller than the third angle. In anaspect, the first angle is smaller than the second angle and the thirdangle is smaller than the fourth angle. In an aspect, the second andfourth side surfaces include proximal ends that relatively smoothlytransition to the body. In an aspect, the distal head comprises a firstundercut and a second undercut, the first and second undercutsrespectively cooperating with the first and third side surfaces to formthe barbs, each of the first and second undercuts having a depth suchthat the barb tips are disposed proximal of the respective undercut. Inan aspect, the body comprises a main portion, a distal neck portion, anda proximal neck portion, the distal and proximal neck portions having across-sectional area smaller than a cross-section area of the mainportion.

In an exemplary aspect, the present disclosure is directed to anintramedullary fixation device used in bone fixation and stabilizationon a patient that includes a longitudinally extending rigid body havinga rigidity sufficient to withstand bending loading applied by thephalanges, with the rigid body having a longitudinal axis extendingthrough at a least a portion of the body. A distal head is disposed at adistal end of the body and sized for insertion into an intramedullarycanal of a phalanx of the patient. The distal head has a central coreportion and a plurality of extending distal wings radially projectingfrom the central core portion. Each distal wing comprises an outersurface portion having an outer perimeter surface portion and a curvedleading surface portion. The curved leading surface portion curves fromthe outer perimeter surface portion and smoothly intersects at thecentral core portion of the distal head. Each wing of the distal headalso comprises a proximally facing trailing surface portionsubstantially perpendicular to the longitudinal axis of the rigid body.The distal head has a first maximum diameter defined by the outerperimeter surface portion of the distal wings and a first wing length.The device also includes a proximal head at a proximal end of the bodysized for insertion into an intramedullary canal of a phalanx of thepatient. The proximal head has a central core portion and a plurality ofproximal wings extending radially outwardly from the central coreportion. Each proximal wing comprises an outer surface portion having anouter perimeter surface portion and a curved leading surface portion.The curved leading surface portion curves from the outer perimetersurface portion and smoothly intersects at the central core portion ofthe proximal head. Each proximal wing also comprises a distally facingtrailing surface portion substantially perpendicular to the longitudinalaxis of the rigid body. The proximal head has a second maximum diameterdefined by the outer perimeter surface portion of the distal wings and asecond wing length, wherein the first maximum diameter of the distalwings is less than the second maximum diameter of the proximal wings,and wherein first wing length of the distal wings is greater than thesecond wing length of the proximal wings.

In an aspect, at least one of the proximal wings is wedge-shaped, suchthat the trailing surface portion has a thickness greater than at thecurved leading surface portion. In an aspect, the body includes acentral region and end regions, with the central region having across-section width greater than the cross-sectional width of the endregions. In an aspect, the central region extends between about 40 and70% of the length of the body. In an aspect, the body comprises a narrowregion adjacent one of the proximal and distal heads, the narrow regionextending from said one of the proximal and distal heads more than 20%of the length of the body. In an aspect, the narrow region is adjacentthe proximal head. In an aspect, the distal head comprises a leading nubdisposed on the distal end of the distal head. In an aspect, the devicecomprises a fixation-promoting coating disposed on the body. In anaspect, the body includes a plantar grade bend in a range of about 5 to15 degrees. In an aspect, the central core has a cross-sectional sizesmaller than a cross-sectional size of the body. In an aspect, the bodyis formed of two rigid elements joined together. In an aspect, thedevice has an overall length, and the proximal and distal heads form notmore than about 30% of the overall length. In an aspect, the centralcore portion on the distal head smoothly connects adjacent wings withoutedges or corners. In an aspect, the wings form a cruciate or plus shapewhen viewed from an end. In an aspect, the device comprises more thanfour distal wings and more than four proximal wings. In an aspect, theplurality of distal wings is symmetrically disposed about the distalhead and wherein the plurality of proximal wings is symmetricallydisposed about the proximal head.

In yet another exemplary aspect, the present disclosure is directed toan intramedullary fixation device used in bone fixation andstabilization on a patient that includes a longitudinally extendingrigid body having a rigidity sufficient to withstand bending loadingapplied by the phalanges, with the rigid body having a longitudinal axisextending through at a least a portion of the body. The device alsoincludes a distal head disposed at a distal end of the body and sizedfor insertion into an intramedullary canal of a phalanx of the patient.The distal head has a central core portion and a plurality of extendingdistal wings radially projecting from the central core portion. Thecentral core portion has an outer surface smoothly intersecting with theadjacent distal wings and including a leading nub. Each distal wingcomprises an outer surface portion having an outer perimeter surfaceportion and a curved leading surface portion, where the curved leadingsurface portion curves from the outer perimeter surface portion andsmoothly intersects at the central core portion of the distal head. Eachwing of the distal head also comprises a proximally facing trailingsurface portion substantially perpendicular to the longitudinal axis ofthe rigid body. The distal head has a first maximum diameter defined bythe outer perimeter surface portion of the distal wings and a first winglength. The device also includes a proximal head at a proximal end ofthe body sized for insertion into an intramedullary canal of a phalanxof the patient. The proximal head has central core portion and aplurality of proximal wings extending radially outwardly from thecentral core portion. The central core portion has an outer surfacesmoothly intersecting with the adjacent distal wings and including aleading nub. Each proximal wing comprises an outer surface portionhaving an outer perimeter surface portion and a curved leading surfaceportion, where the curved leading surface portion curves from the outerperimeter surface portion and smoothly intersects at the central coreportion of the proximal head. Each proximal wing also comprises adistally facing trailing surface portion substantially perpendicular tothe longitudinal axis of the rigid body. The proximal head has a secondmaximum diameter defined by the outer perimeter surface portion of thedistal wings and a second wing length, wherein the first maximumdiameter of the distal wings is less than the second maximum diameter ofthe proximal wings, and wherein first wing length of the distal wings isgreater than the second wing length of the proximal wings, wherein thedevice has an overall length, and the proximal and distal heads form notmore than about 25% of the overall length.

In an aspect, at least one of the proximal wings and is wedge-shaped,such that the trailing surface portion has a thickness greater than atthe curved leading surface portion. In an aspect, the body includes acentral region and end regions, with the central region having across-section width greater than the cross-sectional width of the endregions. In an aspect, the central region extends between about 40% and70% of the length of the body. In an aspect, the body comprises a narrowregion adjacent one of the proximal and distal heads, the narrow regionextending from said one of the proximal and distal heads more than 20%of the length of the body. In an aspect, the narrow region is adjacentthe proximal head.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory innature and are intended to provide an understanding of the presentdisclosure without limiting the scope of the present disclosure. In thatregard, additional aspects, features, and advantages of the presentdisclosure will be apparent to one skilled in the art from the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate embodiments of the devices andmethods disclosed herein and together with the description, serve toexplain the principles of the present disclosure.

FIG. 1 is an illustration of an exemplary intramedullary fixation devicedisposed between and within adjacent phalanges of a toe of a patient inaccordance with one aspect of the present disclosure.

FIGS. 1A-1D are illustrations of exemplary intramedullary fixationdevices disposed between and within adjacent phalanges of a toe of apatient in accordance with different aspects of the present disclosure.

FIG. 2 is an illustration of the exemplary intramedullary fixationdevice of FIG. 1 in accordance with one aspect of the presentdisclosure.

FIG. 3 is an illustration of a side view of the exemplary intramedullaryfixation device of FIG. 2 in accordance with one aspect of the presentdisclosure.

FIG. 4 is an illustration of a cross-sectional view of the exemplaryintramedullary fixation device of FIG. 3 along the lines 4-4 in FIG. 3in accordance with one aspect of the present disclosure.

FIGS. 5-9 are illustrations of another exemplary intramedullary fixationdevice in accordance with one aspect of the present disclosure.

FIG. 10 is an illustration of another exemplary intramedullary fixationdevice in accordance with one aspect of the present disclosure.

FIG. 11 is illustrations of another exemplary intramedullary fixationdevice in accordance with one aspect of the present disclosure.

FIGS. 12-16 are illustrations of another exemplary intramedullaryfixation device in accordance with one aspect of the present disclosure.

FIG. 17 is an illustration of an exemplary intramedullary fixationdevice disposed between and within adjacent phalanges of a hand of apatient in accordance with one aspect of the present disclosure.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the embodimentsillustrated in the drawings, and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the disclosure is intended. Any alterations and furthermodifications to the described devices, instruments, methods, and anyfurther application of the principles of the present disclosure arefully contemplated as would normally occur to one skilled in the art towhich the disclosure relates. In particular, it is fully contemplatedthat the features, components, and/or steps described with respect toone embodiment may be combined with the features, components, and/orsteps described with respect to other embodiments of the presentdisclosure. For simplicity, in some instances the same reference numbersare used throughout the drawings to refer to the same or like parts.

The present disclosure relates to intramedullary systems, methods, anddevices used for bone fixation and stabilization of toes and fingersacross fusion or fracture sites, and treat deformities, including forexample, hammertoe deformities. The intramedullary fixation deviceincludes unique arrow designs on both its proximal and distal ends, andin some embodiments, with the arrow designs varying in size and shape.It is arranged to be completely intramedullary when implanted with noparts of the device exposed outside the skin. Further, it is arranged toresist the rotational and pull-out forces affecting the lesser toes. Itsparticular design shape may help it maintain the initial compressionapplied at insertion.

FIG. 1 shows an exemplary toe 10 having an intermediate phalanx 12 and aproximal phalanx 14. In this example, the toe 10 has been surgicallytreated to correct a deformity such as hammertoe as discussed above.Accordingly, the toe includes an implanted intramedullary fixationdevice 100 disposed therein in accordance with an exemplary aspect ofthe present disclosure. In this example, the device 100 extends betweenand is implanted within the intermediate and proximal phalanges 12, 14.

FIG. 1A shows the exemplary device 100 in greater detail configured anddisposed to anchor in the cortex of the proximal phalanx and theintermediate phalanx. FIG. 1B shows an exemplary device 20 configuredand disposed to anchor in the subchondral bone of the proximal phalanxand in the intermediate phalanx.

FIG. 1C shows an exemplary device 30 configured and disposed to anchorin the subchondral bone of the proximal phalanx, to entirely passthrough the intermediate phalanx, and to anchor in the distal phalanx.

FIG. 1D shows an exemplary device 40 configured and disposed to anchorin the intermediate phalanx and the distal phalanx. The devicesdescribed in greater detail herein may form or be used to form any ofthe devices 100, 20, 30, and 40 shown in FIGS. 1 and 1A-1D, withdimensional changes being a difference between devices. The device 100,as a representative device, is described in detail below.

FIGS. 2-4 show one exemplary embodiment of the device 100 of the presentapplication. The device 100 is designed with a three-dimensionallyconfigured arrow at each end and includes a distal head 102, a proximalhead 104, and a body 106 extending between the distal and proximal heads102, 104. As will become apparent from the below description, theindividual components of the device 100 work in conjunction with oneanother to stabilize bone during arthrodesis procedures and acrossfractures. While the heads are described as proximal and distal heads,it should be understood that the proximal head may be implanted in adistal position and the distal head may be implanted in a proximalposition.

The distal head 102 is formed as a three dimensional arrowhead that issized for placement in an intramedullary canal of a patient. It isconfigured so that edges of the arrowhead grasp the cancellous bone inthe medullary canal as it is inserted, stabilizing the arthrodesis orfusion site during the osseous union. In this exemplary embodiment, thedistal head 102 is formed as a distal end having a distal-most point108. The distal-most point 108 leads the device 100 down the reamed orbroached insertion channel to its final implantation site duringinsertion. In this example, the distal-most point 108 is a sharp pointarranged to glide through tissue within the intramedullary canal to easeinsertion. Other configurations of the arrowhead's tip may result insuccessful insertion based on preparation of the insertion site.

First, second, third, and fourth outer facing surfaces 110, 112, 114,116 intersect at and extend from the distal most point 108 in theproximal direction, forming a four-sided pyramidal shape. Although shownas having four outer facing surfaces, some embodiments include greateror fewer outer facing side surfaces. In the example shown, opposingsurfaces angle away from each other to define a leading angle. Forexample, the opposing first and third outer facing surfaces 110, 114define an angle θrelative to a longitudinal axis 117 of the arrowheadshaped distal head 102. In some examples, the angle θ is in the range ofabout 5 degrees to about 45 degrees. In other examples, the angle θ isin the range of about 7-20 degrees, and in some embodiments, the angleis around 11 degrees. In a similar manner, the opposing second andfourth outer facing surfaces 112, 116 of the arrowhead shaped distalhead 102 form an angle α. In the example shown, the angle α is largerthan the angle θ. The angle α may be selected to be within the range ofabout 15-60 degrees, and in some embodiments, is in the range of about20-45 degrees. In some examples, the angle α is about 30 degrees. Themultiple angles described on the distal head may vary based on the sizeand strength of bone in which the device is to be implanted.

In the embodiment shown, the second and fourth outer facing surfaces112, 116 have rounded outer surfaces. At the proximal end of thesesurfaces, the second and fourth outer facing surfaces 112, 116 have adiameter D within a range of about, for example, 2.5-4.5 mm.

In some embodiments, the diameter D is in a range of about 3.0-4.0 mm,and in one embodiment, the diameter D is about 3.5 mm. In otherembodiments, the second and fourth outer facing surfaces 112, 116 areeach planar surfaces.

Because of the different angles between the opposing first and thirdsurfaces 110, 114 and the opposing second and fourth surfaces 112, 116,the width of the distal head 102 differs from side to side. This iseasily seen by comparing FIGS. 2 and 3, different views of the distalhead 102. This differing width increases resistance to rotation that mayoccur if the device 100 were cylindrical or to a lesser extentsubstantially square, although such embodiments are contemplated.Further, the differing width may permit an implanted device to beremoved, rotated 90 degrees and implanted again while still providingsatisfactory anchoring.

Because of its different widths, the distal head 102 may be sized sothat the diameter D of the head 102 is greater than a longitudinallength L of the distal head 102. In embodiments where the second andfourth outer facing surfaces 112, 116 are planar, the distance betweenthe surface measured at the proximal ends of these surfaces correspondto the diameter D measurements mentioned above. The longitudinal lengthL may be sized in the range of about 1.5-5.5 mm. In one example, thediameter D is around 3.5 mm and the longitudinal length L is about 3 mm.Other sizes however, both larger and smaller, are contemplated, and inone example, the width and the length are substantially equal.

In the example shown, the distal head 102 includes two proximallyprojecting barbs 118, 120. These barbs are configured to engage tissuewithin the intramedullary canal and resist movement and migration and/oraxial displacement within the canal once they have been inserted intothe canal. As can be seen, these barbs 118, 120 are formed by edges ofrespective outer facing surfaces 112, 116 and because of the pyramidalshape of the distal head, the edges lie in substantially parallel lines.

Inner surfaces of the barbs 118, 120 are formed by first and secondundercuts 122, 124 disposed respectively between tips of the barbs 118,120. These are described in prior U.S. patent application Ser. No.13/084,048 to Roman, filed Apr. 11, 2011, incorporated herein byreference.

In some embodiments, the barbs are flexible enough to bend if a hardcortical wall is engaged during insertion, providing a reduction indiameter, and enabling additional advancement into an intramedullarycanal. In one embodiment, the flexing barbs invoke a change in diameterin the range of about 0.1-0.3 mm. In some examples, the barbs aredesigned in such a manner that one or both barbs can be trimmedintra-operatively with a straight pin cutter to reduce the diameter ofthe arrow to fit particularly narrow IM canals. If necessary, thearrowhead tip may be completely removed.

The body 106 extends between and connects the distal head 102 and theproximal head 104. It is a one-piece rigid element structurallyconfigured to withstand loading applied across the joint or fracturebeing supported. It includes a main body portion 130 and necks 132, 134at either end leading to the distal and proximal heads 102, 104. As canbe seen, the main body portion 130 has a diameter larger than that ofthe necks 132, 134. The larger body portion 130 may be easier to graspand secure with a surgical instrument because it has a larger perimetersurface area, while the necks 132, 134 may be sized to permit additionaltissue placement and tissue growth immediately adjacent the undercutsurfaces 122, 124 of the distal and proximal heads 102, 104. This mayresult in more secure and lasting anchoring. Thus, this structuralarrangement may provide space for extra tissue to grow behind thearrowhead to aid in fixation, while still providing a large grippingsurface on the body 106.

Still referring to these figures, the second and fourth outer facingsurfaces 112, 116 are angled and intersect with the body 106 at the neck132. In some examples, the second and fourth outer facing surfaces 112,114 may smoothly transition to the neck and in other examples; thesecond and fourth outer facing surfaces 112, 114 meet the neck 132 at anintersecting angle. In some examples, the neck 132 is formed with arounded perimeter having a diameter substantially similar to thedistance between the proximal ends of the second and fourth outer facingsurfaces 112, 114.

The second or proximal head 104 is, in the example shown, smaller thanthe distal head 102, and extends from the body 106 in the opposingdirection. For clarity and to reduce duplication, much of thedescription above applies to the proximal head 104 and is not repeatedhere with the understanding that the description above applies to theproximal head 104. As such, the proximal head includes four mainsurfaces forming an arrowhead, labeled as fifth, sixth, seventh, andeighth surfaces. As can be seen, some of these surfaces form an angle βand others form an angle φ relative to the longitudinal axis. In oneembodiment, the angle β is smaller than the angle θ. In someembodiments, the angle β ranges from about 7-25 degrees, and in oneembodiment is 11 degrees. The angle φ may be within a range discussedabove relative to the angle α, and in one embodiment, is equal to theangle α.

In this embodiment, the proximal head 104 is formed with trailing edgesurfaces 140 instead of projecting barbs. The trailing edge surfaces 140enable bone ingrowth immediately adjacent the trailing edge surfaces,resulting in a relatively quick purchase of the proximal head 104 duringhealing. The trailing edge surfaces 140 extend substantiallyperpendicular to the longitudinal axis 117 of the device 100.

The proximal head 104 is sized and configured to be implanted in thesubchondral bone at the base of the proximal phalanx. While thisproximal head 104 has a smaller diameter and length than the largerdistal head 102, because it is implanted in the more dense subchondralbone at the base of the proximal phalanx, the proximal head may achievea stability and resistance to migratory forces that is similar to thatof the larger distal head 102, which is shaped and configured to beinserted in the less dense cancellous bone of the middle phalanx.

In the example shown the distal head 102 has a length that is about 1.5times the length of the proximal head 104. Likewise, it has an overallwidth about 1.3-1.5 times the width of the proximal head 104.

Some embodiments of the device include a body having a plantar gradebend. Different embodiments include a bend that may be selected in therange of about 5-25 degrees. In some examples, the bend is selected tobe about a 15 degree bend, while yet other embodiments the bend isselected to be about a 10 degree bend, an in another, about a 5 degreebend.

FIGS. 5-9 show another exemplary embodiment of a device, referencedherein as a device 200. The device 200 is designed with athree-dimensionally configured arrow at each end and includes a distalhead 202, a proximal head 204, and a body 206 extending between thedistal and proximal heads 202, 204 and having a longitudinal axis 207.Features consistent with those described above will not be repeated herefor the sake of simplicity, but it is understood that the relevantdescription of features relative to other embodiments described hereinalso apply to the device 200.

The distal head 202 includes a central core portion 208 and a pluralityof radially extending distal wings 210. The core portion 208 extendsalong the longitudinal axis 207 of the body 206 and includes the distalend 212. In this example, the distal end 212 is rounded or blunt end toprovide smooth insertion into the medullary canal. In addition, becauseof its rounded shape, when implanted in techniques using bored or reamedholes, the surgeon can feel tactilely when the implant is inserted tothe depth of the bored or reamed hole because the rounded end resistsfurther insertion at low insertion forces. However, the surgeon maystill insert the device into the intramedullary canal beyond the end ofthe bored or reamed area by applying additional force. In thisembodiment, the distal end 212 is formed of a convexly shaped leadingnub 214 extending from the surfaces leading to the wings 210.

The plurality of wings 210 extend radially from the core portion 208 anddefine the outer shape of the distal head 202. In the embodiment shown,the head 202, as measured from wing to wing, has a diameter sized to fitwithin an intramedullary canal of a phalanx and more particularly,within a medullary canal of a middle phalanx.

The wings themselves include an outer surface portion 216, a trailingsurface portion 222, and lateral sides 224. In the exemplary embodimentshown, the outer surface portion 216 of the wings 210 includes acylindrical surface portion 218 and a curved leading surface portion220. The outer perimeter surface portion 218 extends in the longitudinaldirection and then intersects with the curved leading surface portion220. In this example, the outer perimeter surface portion 218 of theplurality of wings 210 together also defines an outer diameter or outerwidth W1 (FIG. 6) of the distal head 202. In some embodiments, the headhas a width sized within the range of about 2.0 mm to 4.5 mm. In oneembodiment, the width W1 is sized within the range of about 3.0 mm to4.0 mm. In one embodiment, the width W1 is sized within the range ofabout 3.5 mm. In some embodiments, the outer perimeter surface portion218 of the wings 210 has a curved outer surface that lies along theboundary of a cylindrical shape at the maximum diameter or width W1, asrepresented by the dashed lines in FIG. 6. Some embodiments are sized toaccommodate a particular bone quality and intramedullary canal diameter.For example, for softer bone quality or for larger canals, the diameterof the distal head may be selected to be within a range of 2.5 mm to 5.0mm.

Extending from the outer perimeter surface portion 218, the wings 210include the curved leading surface portion 220. The curved leadingsurface portion 220 faces at least partially in the direction of thedistal end 212, and curves from the outer surface portion 216 toward andsmoothly intersects with the core portion 208. In some embodiments, thecurved leading surface portion 220 has a radius within a range of about1 mm to 4 mm, and in some embodiments has a radius within a range ofabout 1.5 mm to 2.5 mm. In one embodiment, the radius is 2 mm.

The trailing surface portion 222 is a surface extending radially inwardfrom the outer surface portion 216 toward the longitudinal axis of thedevice 200 and intersects with the core portion 208. In the embodimentshown, the trailing surface portion 222 has a surface that liessubstantially normal to the longitudinal axis 207, although in otherembodiments, it may be angled obliquely relative to the longitudinalaxis. A rounded, distally projecting edge 228 connects the trailingsurface portion 222 to the outer perimeter surface portion 218 of theouter surface portion 216.

In the embodiment shown, each wing 210 includes two lateral sides 224.In the example shown, the lateral sides extend from the outer surfaceportion 216 to the core portion 208. Depending on the embodiment, theselateral sides 224 may be formed in parallel planes or may bewedge-shaped. The thickness of the wing 210 is defined by the distancebetween the lateral sides 224 and the pull-out resistance is determinedby the thickness of the wing 210 at the trailing surface portion. A wing210 having lateral sides 224 in parallel planes will have uniformthickness and may be easier to implant while still providing rotationalstability.

In other embodiments however, these lateral sides 224 may be formed ofnonparallel planes and may form a wedge-shape. For example, oneembodiment includes a wing 10 having a leading portion having athickness about 0.38 mm at the leading end and a thickness of about 0.52mm at the trailing end. Other angles and dimensions are alsocontemplated. Accordingly, the wings are thinner toward the leading endthan the trailing end. Embodiments with wedge-shaped wings may requiremore force to implant. However, they may also provide closer contactbetween the bone and the wing 210 because the wing may become graduallythicker from the leading edge to the trailing edge. In addition,increasing thickness of the wing toward the trailing edge maximizes theresistance to pull-out because the wing at the trailing surface portionis at its thickest location.

In some embodiments, the lateral sides 224 are nonplanar and have acurved surface that promotes interference with bone tissue to resistmigration and rotation. Some embodiments include wings that vary by wingthickness. For example, some embodiments include two wings having afirst thickness and two additional wings having a second thicknessgreater than the first thickness. The core portion 208 smoothly connectsand spans between adjacent wings with a cylindrical surface 232 thatextends the length of the wings 210.

Because the distal end 212 has a smooth bullet-nose shape, thelikelihood of the distal end catching on the cortex and preventing theimplant from being advanced smoothly may be diminished. Duringinsertion, the wings 210 act as sled runners to help the device 200slide easily down a reamed pilot hole. In addition, the smooth andcurved leading surface portion 220 on the wings 210 may enable theimplant to be self-centering during the insertion process.

While the distal head 202 is shown having four wings 210 forming a plusor cruciate configuration, other embodiments include a different numberof wings. One embodiment includes three wings, while another embodimentincludes two wings. Yet other embodiments include more than four wings.Depending on the embodiment, the distal head 202 may comprise betweenthree and eight distal wings 210 arranged in a symmetric or asymmetricmanner. Some examples have distal wings forming a cruciate or plusshape, an X shape, a five-sided star shape, or a six-sided star shape,or a four-wind dorsally (like an underlined V), among other possiblecombinations. The number of wings may affect the pull-out resistance ofthe device 200. For example, a balance between the number of wings andtheir relative size may permit the device to be designed to achieve adesired pull-out resistance. Reducing the diameter of the wings maypermit the device 200 to be implanted within smaller diameterintramedullary canals while still providing suitable resistance topull-out. Some embodiments have the wings of the proximal head rotatablyoffset from the wings of the distal head. For example, while the wingson the distal head may be disposed at 3, 6, 9, and 12 o'clock, the wingson the proximal head may be disposed at 2, 5, 8, and 11 o'clock. In someembodiments, the wings are offset by 45 degrees.

Because of the central core portion 208 design, the pilot holepreparation may be done with a rotary motion, such as a power or manualreamer or drill, thereby possibly reducing the need for the step ofbroaching the pilot hole to form a rectangular cavity.

Some embodiments include a head length that is minimized in order topermit as much bone growth behind the trailing surface portion possibleto contribute to resistance to pull-out. In one embodiment, the lengthof the distal head is within the range of about 2.0 mm to 3.0 mm. Othersizes are also contemplated.

The blade orientation for the distal head 202 provides not onlyresistance to rotation and pull-out but also may ease pulling the middlephalanx over the distal head 202 as it the portion of the device thatprotrudes from the proximal phalange during insertion.

The proximal head 204 includes a central core portion 240 and aplurality of radially extending wings 242. Many features of the proximalhead 204 are similar to that of the distal head 202 and not all thefeatures are re-described here, recognizing that one of ordinary skillwould understand that features and alternatives described relative tothe distal head 202 have equal applicability to the proximal head 204.Like the core portion 208 of the distal head 202, the central coreportion 240 extends along the longitudinal axis 207 of the body 206. Thecore portion 240 includes a proximal end 244. In this example, the coreportion 240 and the proximal end 244 differs in shape as describedbelow, while still maintaining a rounded or blunt end to provide smoothinsertion into the medullary canal. In this embodiment, the core portionproximal end 244 includes a conical surface portion 256 that connectsthe leading surface portion 250 and includes a convexly shaped leadingnub 245 extending from the surfaces leading to the wings 242.

The plurality of wings 242 extend radially from the core portion 240 anddefine the outer shape of the proximal head 204. In the embodimentshown, the head 202, as measured from wing to wing, has a diameter sizedto fit within an intramedullary canal of a phalanx and moreparticularly, within a canal of a proximal phalanx.

The wings 242 themselves include an outer surface portion 246, atrailing surface portion 252, and lateral sides 254. In the exemplaryembodiment shown, the outer surface portion 246 of the wings 242includes an outer perimeter surface portion 248 and a curved leadingsurface portion 250. The outer perimeter surface portion 248 extends inthe longitudinal direction and then intersects with the curved leadingsurface portion 250. In this example, the outer perimeter surfaceportion 248 of the plurality of wings 242 together also defines an outerdiameter or outer width W2 (FIG. 9) of the distal head 202. In someembodiments, the proximal head 204 has a width sized within the range ofabout 1.0 mm to 3.5 mm. In one embodiment, the width W2 is sized withinthe range of about 2.0 mm to 3.0 mm. In one embodiment, the width W2 issized within the range of about 2.5 mm. In some embodiments, the outerperimeter surface portion 248 of the wings 242 has a curved outersurface that lies along the boundary of a cylindrical shape at themaximum diameter or width W2, as represented by the dashed lines in FIG.9. Extending from the outer perimeter surface portion 248, the wings 242include the curved leading surface portion 250. The curved leadingsurface portion 250 curves from the outer surface portion 216 toward andsmoothly intersecting with the conical surface portion 256 of the coreportion 208. In some embodiments, the curved leading surface portion 250has a radius sized in the ranges as described with reference to thecurved leading surface portion 220. In one embodiment, the coveredleading surface portions 220, 250 have the same radius.

The trailing surface portion 252 extends radially inward from the outersurface portion 246 toward the longitudinal axis of the device 200 andintersects with the core portion 240. A rounded edge 258 connects thetrailing surface portion 252 to the outer perimeter surface portion 248of the outer surface portion 246.

Each wing 242 includes two lateral sides 254. In one embodiment, thethickness of the wings 242 is measured between the lateral sides 254 andis in the range of 0.020 mm and 0.060 mm. In one embodiment, the wingsare wedge shaped and taper from a thickness of 0.37m at its leading endto 0.053 at its trailing end.

As indicated above, the overall length of the proximal head 204 isgreater than that of the distal head 202. However, the length can beshortened to enhance pull-out resistance. For example, the resistance topull-out may increase as the distance from the trailing surface portionof the distal or proximal head to the osteotomy increases. For thedistal head 202 that is implanted in the middle phalanx, a shorter headmay offer resistance to rotation and still increase the distance fromthe trailing surface portion of the implant wings to the osteotomy sitewhen implanted to the same depth. Because the trailing surface portionof the wing on the shorter head is farther from the fracture site, aradiograph would give the appearance of the device being more deeplyimplanted in the middle phalanx. As such the distal head 202 with itslarger diameter is intended for implantation in the medial phalanx andthe proximal head 204 with its smaller diameter is intended forimplantation in the proximal phalanx.

The body 206 is a rigid shaft extending between and connecting thedistal head 202 and the proximal head 204. In the embodiment shown, thebody 206 is cylindrically shaped and has a substantially smooth exteriorsurface. In one embodiment, the body 206 has a diameter or across-sectional thickness within a range of about 1.2 mm to 2.0 mm. Inone embodiment, the body 206 has a diameter or a cross-sectionalthickness of about 1.6 mm.

Other sizes, larger and smaller are contemplated. The body 206 includesa necked-down region adjacent the proximal and distal head as the bodymerges with the central core portion.

In some embodiments, the proximal and distal heads form about a 30% orless of the overall length of the device. In one example, the distalhead has a length of about 2.5 mm, the proximal head has a length ofabout 3.0 mm, and the body has a length about 13.5 mm or greater.

In the embodiment shown, the body 206 has a substantially constantdiameter. However some embodiments have body diameters that vary alongthe length of the body 206 to correspond to forces and to increase thearea of the arrowhead tip resisting pull-out and rotational forces. Twosuch embodiments are described below relative to FIGS. 10 and 11.

FIG. 10 shows another embodiment of a device referenced herein by thenumeral 300. The device 300 includes a distal head 302, a proximal head304, and a body 306. The distal and proximal heads 302, 304 includefeatures similar to those described above, and the descriptions apply tothis embodiment, recognizing that the size ratio of the different headsmay differ on the device 300. Here, the proximal head 304 include a coreportion 308 and wings 310. The body 306 in this embodiment includes atapered shaft region 312 that extends along a substantial portion of thebody 306.

In this embodiment, the size ratio of tapered shaft region 312 to theadjacent core portion 308 of the head may be selected to be minimized.This may permit the body 306 to be deeply embedded within the phalanxwith a minimal amount of tissue disruption. Some embodiments have lessthan a 1:1.5 tapered shaft region to core portion size ratio, whileother embodiments have a 1:1 size ratio. Other sizes and ratios arecontemplated. The reduced diameter of the tapered shaft region 308 mayextend less than half the distance of the body 306 so that the thickerregion of the body 306 may be disposed at the fusion region when thedevice 200 is implanted. In the exemplary embodiment shown, the taperedshaft region 312 extends for a length of more than about 15% of thelength of the entire body. In one embodiment, the tapered shaft region312 extends from the proximal head a distance between about 15% and 45%of the length of the body 306. In some examples, the tapered shaftregion 312 extends a distance within a range of about 20% and 30% of thelength of the body 306. This may provide a suitable region for boneingrowth behind the proximal head 304, while still having the thickerportion of the body at the osteotomy site. While referred to as atapered shaft region 312, the narrow region of the shaft may also becylindrical, and may be referred to as a narrow region.

This also may permit the proximal head 304 to be embedded in thesubchondral bone of the proximal phalanx. Reducing the ratio of the coreportion 308 to the body 306 may increase the resistance to rotation andpull-out. In one embodiment, the body diameter or width is set at adiameter of 1.0 mm so that an additional 0.25 mm per wing (0.5 mm total)is available to resist rotational forces. The increased area resistingpull-out is also 0.25 mm per wing multiplied by the width of the wing310 at the trailing surface portion, multiplied by the number of wings310. In this embodiment, a reamer width would be reduced to the width ofthe body 306 at the narrowest point.

In the example shown, the thickness or cross-sectional width of the body306 that aligns with the osteotomy site and into the distal tip of theimplant would remain at the thickest portion of the body 306, which inone embodiment, is 1.6 mm.

FIG. 11 shows another embodiment of a device, reference herein by thenumeral 400. The device 400 includes a distal head 402, a proximal head404, and a body 406. The distal and proximal heads 402, 404 includefeatures similar to those described above, and the descriptions apply tothis embodiment, recognizing that the size ratio of the different headsmay differ on the device 400. In this embodiment, the body 406 includesa central region 410 of increased thickness. Accordingly, the body 406includes narrower regions 412 at the distal and proximal ends, and thesenarrow further at necks 414 to form the respective distal and proximalheads 402, 404.

Here, the central region 410 may provide greater strength and a tighterfit at the site of the osteotomy. In one embodiment, the width ordiameter of the body 106 in the central region 410 is within a range ofabout 1.8 mm-2.2 mm to enhance the fixation at the osteotomy site and tostabilize the device by helping to reduce play of the device 200. Thismay also increase the strength of an already strong implant at the pointof greatest potential stresses. In such an embodiment, the reamerdiameter may remain at a size to accommodate the narrower regions 412.For example, the narrow regions 412 may have a diameter of about 1.6 mm,and therefore, in some examples, the reamer diameter would also be 1.6mm. In one embodiment, the central region 410 may extend about 40-70% ofthe length of the body. In other embodiments, the central region extendsabout 40-60% of the length of the body.

Some embodiments of the bodies disclosed herein include a coating ortissue growth material. For example, some embodiments include anaggressive porous material or coating that is “sticky” to tissue. Someexamples include a bone-growth promoting substance, such as, forexample, a hydroxyapatite coating formed of calcium phosphate,tricalcium phosphate

(TCP), and/or calcium carbonate. Alternatively, osteoinductive coatings,such as proteins from transforming growth factor (TGF) beta superfamily,or bone-morphogenic proteins, such as BMP2 or BMP7, may be used. Thesecoatings may increase adhesion to cancellous bone, increasing resistanceto pull-out and rotational forces. They also may accelerate bonyingrowth and accelerate consolidation of the bone. The coating may beapplied along the entire body of the device, or may be applied onlyalong a specific region, such as a region, such as the half of the bodyadjacent the distal head, for example. FIG. 8 shows one example of acoating region, identified by the box labeled CR. The coating may bearranged in other ways also.

Although shown as cylindrical, any of the bodies disclosed herein mayhave a cross-section of any suitable shape, and may include, forexample, a shaft shape that is triangular shaped, square shaped or onewith edges rather than cylindrical. These types of body cross-sectionscan provide additional resistance to rotational forces. In anotherexample, edges emerging from the body can serve to provide additionalfixation.

In some embodiments, the proximal head 204 is sized and configured to beembedded in the subchondral bone at the base of the proximal phalanx.The rounded blunt tip may require greater force than the sharper,pointier arrow of earlier devices to progress farther into thesubchondral bone than the prepared hole provides. Accordingly, the bluntbullet nose may prevent the implant from advancing past the end of thereamed pilot hole.

In one embodiment, the length of the proximal head is about 2.0 mm inthe longitudinal direction. This length permits the addition of one ortwo additional wings that may increase both the level of the resistanceto rotation and pull-out without increasing the length of the arrowhead.Increasing the length could adversely affect the pull-out resistance invivo, for example, if the longer arrowhead were to not be completelyembedded in subchondral bone. In this example, the wings are formed sothat the head is substantially symmetrical. In other examples however,the proximal head comprises between three and eight proximal wingsarranged in a symmetric or asymmetric manner. Some examples haveproximal wings forming a cruciate or plus shape, an X shape, afive-sided star shape, or a six-sided star shape, or a four-winddorsally (like an underlined V), among other possible combinations.

FIGS. 12-16 show an additional embodiment of a device, referenced hereinby the numeral 500, including a distal head 502, a proximal head 504,and a body 506. The distal and proximal heads 502, 504 include featuressimilar to those described above, and the descriptions apply to thisembodiment, recognizing that the size ratio of the different heads maydiffer on the device 500. In this embodiment, the distal and proximalhead each include three wings radially extending from a central core. Ascan be seen, and consistent with the description above, the distal headhas a greater width and a smaller length than the proximal head. Here,as can be seen in the end views shown in FIGS. 13 and 14, the wings ofthe distal head and the proximal head are rotationally offset. Sincethere are three wings, they are rotationally offset by 60 degrees.

The devices may be implanted using any of a number of surgicalinstruments or tools, including for example, a reamer, a broach, and aninsertion forceps. These instruments are described in detail in priorU.S. patent application Ser. No. 13/084,048 to Roman, filed Apr. 11,2011, and incorporated herein by reference.

Furthermore, the devices disclosed herein may be provided as a kit incombination with a plurality of devices of different sizes or theinstruments themselves. One exemplary kit includes a device as describedabove, with the reamer, the broach, and the insertion forceps. Otherkits are described in prior U.S. patent application Ser. No. 13/084,048to Roman, filed Apr. 11, 2011, and incorporated herein by reference.

The devices herein may be used in exemplary surgical methods forimplanting the device for the treatment or correction of bonedeformities. When implanted, the arrowhead configuration of both thedistal and proximal heads captures bone on both sides of the fusion orfracture site, and may provide internal stability. This is accomplishedby pressing and locking the distal and proximal heads into thesurrounding bone. The body of the device extends from each head(proximal and distal) and is the portion of the implant that crosses orspans the fusion or fracture site.

It should be noted that the exemplary devices described herein may beused for treatments such as hammertoe, and in some examples, may be usedto treat conditions in the fingers of a hand, or alternatively may beused to treat bone fractures. FIG. 17 is one example showing an exampledevice, which could be any of the devices disclosed herein implantedwithin phalanges of the hand. In addition, removal of the device may berelatively easier than prior, conventional devices. For example, toremove the device, the cylindrical main body may be first cut, and thena cannulated drill may be fit over the cylindrical main body and drilledover to remove bony on-growth from the cylindrical body so that thearrowhead tip can be removed without tearing the bone. This may preventthe health care provider from having to cut the cortical bone in orderto remove the implant. Accordingly, the cylindrical shape of the mainbody may help reduce a chance of compromising cortical bone duringrevision surgeries. Uses of the device may include but are not limitedto hand surgery, orthopedic surgery, plastic surgery, and podiatricsurgery. In addition, the implant may be inserted in a variety of anglesthat differ from its intended position in medullary bone. In someexamples, the implant may also be placed through cortical bone andtendon of the hand or foot.

In some examples, the device is machined from a single piece of 316Lstainless steel, making it a weld-less, single monolith structure. Inother embodiment, it may be formed of two structures welded or brazedtogether, as shown in the cross-sectional view in FIG. 4. Variouslengths may be provided to meet patient sizing restrictions. The overalllengths of the device may be in the range of 10 mm to 40 mm, while somelengths are within the range of 15 mm to 25 mm. When the device isformed of a single piece of metal, potential stress-risers occurringfrom welds or adhesives are eliminated and there is no need to assembleintra-operatively. Further, the material and size are selected so thatthe device has bending and fatigue characteristics able to endure theforces exerted on the lesser toes.

In some examples, the arrowheads may be reconfigured at differentpositions to one another and may obtain the same stability to thearthrodesis/fracture site. For example, some embodiments have a proximalarrow vertical to the shaft or a distal arrow horizontal to the shaft.The same can be said for different angle increments to each arrow.

Persons of ordinary skill in the art will appreciate that theembodiments encompassed by the present disclosure are not limited to theparticular exemplary embodiments described above. In that regard,although illustrative embodiments have been shown and described, a widerange of modification, change, and substitution is contemplated in theforegoing disclosure. It is understood that such variations may be madeto the foregoing without departing from the scope of the presentdisclosure. Accordingly, it is appropriate that the appended claims beconstrued broadly and in a manner consistent with the presentdisclosure.

We claim:
 1. An intramedullary fixation device, comprising: a rigid bodyhaving a longitudinal axis and comprising first and second neck regions;an arrowhead-shaped distal head at a distal end of the rigid bodycomprising a distal end of the device and having first, second, thirdand fourth outwardly facing side surfaces, each of the first and thirdside surfaces having a proximally projecting edge forming a tip of abarb configured to engage tissue and inhibit rotational movement andinhibit axial movement of the distal head in a proximal direction, thebarbs comprising undercut surfaces and first trailing edge surfacesextending from the tips and intersecting with the undercut surfaces, theundercut surfaces extending from the first trailing edge surfacesdistally and to the first neck region of the rigid body such that thefirst trailing edge surfaces are disposed proximal of the undercutsurfaces, the distal head having a first dimensional width measuredbetween the tips of the barbs; and an arrowhead-shaped proximal head ata proximal end of the rigid body comprising a proximal end of the deviceand having fifth, sixth, seventh and eighth outwardly facing sidesurfaces, each of the fifth and seventh side surfaces having a distallyprojecting edge forming a tip, the proximal head comprising secondtrailing edge surfaces extending from the tips thereof, the secondtrailing edge surfaces extending in a direction substantiallyperpendicular to the longitudinal axis and intersecting with the secondneck region of the rigid body, the proximal head having a seconddimensional width measured between the tips thereof, the firstdimensional width being greater than the second dimensional width. 2.The intramedullary fixation device of claim 1, wherein the first andthird side surfaces of the distal head are opposed from each other andform a first angle, and the second and fourth side surfaces are opposedfrom each other and form a second angle, the second angle beingdifferent than the first angle.
 3. The intramedullary fixation device ofclaim 2, wherein the first angle is smaller than the second angle. 4.The intramedullary fixation device of claim 1, wherein the first,second, third and fourth side surfaces of the distal head are planarsurfaces that forms a pyramidal shape.
 5. The intramedullary fixationdevice of claim 1, wherein the fifth and seventh side surfaces of theproximal head are opposed from each other and form a third angle, andthe sixth and eighth side surfaces are opposed from each other and forma fourth angle, the third angle being different than the fourth angle.6. The intramedullary fixation device of claim 5, wherein the thirdangle is smaller than the fourth angle.
 7. The intramedullary fixationdevice of claim 1, wherein the fifth, sixth, seventh and eighth sidesurfaces of the proximal head are planar surfaces that forms a pyramidalshape.
 8. The intramedullary fixation device of claim 1, wherein thefirst and third side surfaces of the distal head are opposed from eachother and form a first angle, the second and fourth side surfaces of thedistal head are opposed from each other and form a second angle, thefifth and seventh side surfaces of the proximal head are opposed fromeach other and form a third angle, and the sixth and eighth sidesurfaces of the proximal head are opposed from each other and form afourth angle.
 9. The intramedullary fixation device of claim 8, whereinthe second angle is different than the first angle, and the third angleis different than the fourth angle.
 10. The intramedullary fixationdevice of claim 8, wherein the first angle is larger than the thirdangle.
 11. The intramedullary fixation device of claim 1, wherein thefirst trailing edge surfaces of the distal head extend from the tips ina direction substantially perpendicular to the longitudinal axis. 12.The intramedullary fixation device of claim 1, wherein the rigid bodyfurther comprises a main portion, the first and second neck portionshaving a cross-sectional area smaller than a cross-section area of themain portion.
 13. The intramedullary fixation device of claim 1, whereinthe distal head is sized to fit within an intramedullary canal of adistal portion of a first bone, and the proximal head is sized to fitwithin an intramedullary canal of a proximal portion of a second bone.14. The intramedullary fixation device of claim 1, wherein the secondand fourth side surfaces include proximal ends that relatively smoothlytransition to the rigid body.
 15. The intramedullary fixation device ofclaim 1, wherein the distal end of the distal head forms a sharp point,and the proximal end of the proximal head forms a sharp point.
 16. Theintramedullary fixation device of claim 1, wherein the first dimensionalwidth is within the range of about 1.3-1.5 times the second dimensionalwidth.
 17. The intramedullary fixation device of claim 1, wherein thedistal head defines a first longitudinal length and the proximal headdefines a second longitudinal length, the first length being greaterthan the second length.
 18. The intramedullary fixation device of claim17, wherein the first longitudinal length is about 1.5 times the secondlongitudinal length.
 19. The intramedullary fixation device of claim 1,wherein the distal head defines a first longitudinal length, and whereinthe first dimensional width is greater than the first longitudinallength.
 20. The intramedullary fixation device of claim 1, wherein therigid body includes a bend within the range of about 5-25 degrees.